TREM2 and Alzheimer disease: Recent studies suggest that impaired Trem2-Akt-mTOR signaling in AD patients carrying TREM2 risk variants and in Trem2-deficient mice with AD-like microglia affects autophagy and metabolism [34] and decreases the ability of microglia to form a protective barrier around β-amyloid plaques, leading to axonal dystrophy [114].